Automatic version bump

[mmicko]

To be able to enforce that all is going on main using PRs, created a change in Makefile that will update version number to proper one, and in case of tarball we will have +post but still there will be good git commit in version string.

Note that there is no more then need for github action for bumping version, and also during release procedure, we still need to change YOSYS_VER which is fine, but also to comment line YOSYS_VER := $(YOSYS_VER)+post so we can distinct release and non-release builds, for New cycle commit we are going to uncomment this line.

[KrystalDelusion]

Possible problem here with divergent branches. Currently main is the source of truth for version numbers, and any time we see a version number we know that was the last version of main. With this change we could have two different (e.g.) v0.64+17 depending on which branch you're on. Say somebody reports an issue with the v0.64+14 release version, I've got v0.64+17 installed for testing but it actually branched from main after v0.64 and doesn't reproduce. With the current versioning system I would see my version is behind the reported version and checkout latest main. But if my version was higher than theirs I might instead think that the issue had been resolved and ignore it. If both versions were the same I would see a difference in the sha, but if the versions are different then there is no way to know at a glance that they are from different branches.

I don't know what the solution here is (other than changing my workflow to use PROGRAM_PREFIX and using aliases to choose between release-yosys and dev-yosys or something), but for me personally I see this change as potentially doing more harm than good.